Light emitting device, method of manufacturing the same and manufacturing apparatus therefor

ABSTRACT

A light emitting device having high definition, a high aperture ratio, and high reliability is provided. The present invention achieves high definition and a high aperture ratio with a full color flat panel display using red, green, and blue color emission light by intentionally forming laminate portions, wherein portions of different organic compound layers of adjacent light emitting elements overlap with each other, without depending upon the method of forming the organic compound layers or the film formation precision.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device, in particular,the present invention relates to an organic light emitting device (OLED)having a light emitting element formed on a substrate having aninsulating surface. Further, the present invention relates to an organiclight emitting module on which ICs and the like, including a controller,are mounted to an organic light emitting panel. Note that the termsorganic light emitting panel and organic light emitting module bothrefer to light emitting devices in this specification. The presentinvention additionally relates to an apparatus for manufacturing thelight emitting device.

In this specification, semiconductor devices correspond to generaldevices functioning by use of semiconductor characteristics. Therefore,a light emitting device, an electro-optical device, a semiconductorcircuit and an electronic device are all included in the category of thesemiconductor device.

2. Description of the Related Art

Techniques of forming TFTs (thin film transistors) on substrates havebeen progressing greatly in recent years, and developments in theirapplication to active matrix display devices is advancing. Inparticular, TFTs that use polysilicon films have a higher electric fieldeffect mobility (also referred to as mobility) than TFTs that useconventional amorphous silicon films, and therefore high speed operationis possible. Developments in performing control of pixels by formingdriver circuits made from TFTs that use polysilicon films on a substrateon which the pixels are formed have therefore been flourishing. It hasbeen expected that various advantages can be obtained by using activematrix display devices in which pixels and driver circuits are mountedon the same substrate, such as reductions in manufacturing cost,miniaturization of the display device, increases in yield, and increasesin throughput.

Furthermore, research on active matrix light emitting devices usingorganic light emitting elements as self light emitting elements(hereinafter referred to simply as light emitting devices) has becomemore active. The light emitting devices are also referred to as organicEL displays (OELDs) and organic light emitting diodes (OLEDs).

TFT switching elements (hereinafter referred to as switching elements)are formed for each pixel in active matrix light emitting devices, anddriver elements for performing electric current control using theswitching TFTs (hereinafter referred to as electric current controlTFTs) are operated, thus making EL layers (strictly speaking, lightemitting layers) emit light. For example, a light emitting devicedisclosed in JP 10-189252 A is known.

Organic light emitting elements are self light emitting, and thereforehave high visibility. Backlights, necessary for liquid crystal displaydevices (LCDs), are not required for organic light emitting elements,which are optimal for making display devices thinner and have nolimitations in viewing angle. Light emitting devices using organic lightemitting elements are consequently being focused upon as substitutes forCRTs and LCDs.

Note that EL elements have a layer containing an organic compound inwhich luminescence develops by the addition of an electric field(electroluminescence) (hereinafter referred to as EL layer, an anode,and a cathode. There is light emission when returning to a base statefrom a singlet excitation state (fluorescence), and light emission whenreturning to a base state from a triplet excitation state(phosphorescence) in the organic compound layer, and it is possible toapply both types of light emission to light emitting devicesmanufactured by the manufacturing apparatus and film formation method ofthe present invention.

EL elements have a structure in which an EL layer is sandwiched betweena pair of electrodes, and the EL layer normally has a laminatestructure. A “hole transporting layer/light emitting layer/electrontransporting layer” laminate structure proposed by Tang et al. ofEastman Kodak Co. can be given as a typical example. This structure hasextremely high light emitting efficiency, and at present almost alllight emitting devices undergoing research and development employ thisstructure.

Further, a structure in which: a hole injecting layer, a holetransporting layer, a light emitting layer, and an electron transportinglayer are laminated in order on an anode; or a hole injecting layer, ahole transporting layer, a light emitting layer, an electrontransporting layer, and an electron injecting layer are laminated inorder on an anode may also be used. Fluorescent pigments and the likemay also be doped into the light emitting layers. Further, all of thelayers may be formed by using low molecular weight materials, and all ofthe layers may be formed by using high molecular weight materials. Thelayers may also include inorganic materials such as silicon.

Note that all layers formed between a cathode and an anode are referredto generically as EL layers in this specification. The aforementionedhole injecting layer, hole transporting layer, light emitting layer,electron transporting layer, and electron injecting layer are thereforeall included in the category of EL layers.

Both low molecular weight organic compound materials and high molecularweight (polymer) organic compound materials are undergoing research asorganic compound materials for EL layers (strictly speaking lightemitting layers) which can be regarded as a main EL element.

Ink jet methods, evaporation, and spin coating are known as methods forforming films of these organic materials.

However, with these methods the film formation precision is not veryhigh. Wide gaps are therefore designed between different pixels, andinsulators referred to as banks are formed between pixels, whenconsidering the manufacture of full color, flat panel displays usingred, green, and blue colors of light emission.

Further, the demands for high definition, high aperture ratio, and highreliability are increased for full color flat panel displays using red,green, and blue color light emission. These demands become a bigproblem, however, in that the pitch between pixels becomes finer alongwith making the light emitting device higher in definition (increasingthe number of pixels) and reducing the size of the light emittingdevice. Furthermore, the demands for increases in productivity andreductions in cost also increase.

SUMMARY OF THE INVENTION

An object of the present invention is therefore to achieve highdefinition, and a high aperture ratio, in a full color flat paneldisplay. using red, green, and blue color light emission, withoutdepending on the organic compound layer film formation method or thefilm formation precision, by intentionally making a portion of differentorganic compound layers of adjacent light emitting elements overlap witheach other.

Note that, although the luminance of light emission in the portionswherein parts of different organic compound layers overlap with eachother falls to approximately 0.1% of its normal value, and the amount ofelectric current flowing there also drops to 0.1% of its normal value,it is possible to have light emission of an order capable of beingsufficiently recognized, provided that a high voltage (equal to orgreater than approximately 9 V) is applied.

According to a structure 1 of the present invention disclosed in thisspecification, there is provided a light emitting device comprising aplurality of light emitting elements, each having a cathode, an organiccompound layer contacting the cathode, and an anode contacting theorganic compound layer, in which one light emitting element has: a firstlight emitting region structured by the cathode, the organic compoundlayer contacting the cathode, and the anode contacting the organiccompound layer; and a second light emitting region structured by thecathode, a laminate organic compound layer contacting the cathode, andthe anode contacting the laminate organic compound layer.

In the above-mentioned structure 1, the laminate organic compound layeris a laminate layer of: the organic compound layer in the first lightemitting region; and an organic compound layer of a light emittingelement adjacent to the one light emitting element and having adifferent color light emission therefrom.

Further, three types of light emitting elements are suitably disposedfor full color RGB, and according to a structure 2 of the presentinvention disclosed in this specification, there is provided a lightemitting device comprising a plurality of light emitting elements, eachhaving a cathode, an organic compound layer contacting the cathode, andan anode contacting the organic compound layer, in which a first lightemitting element having a first organic compound layer, a second lightemitting element having a second organic compound layer, and a thirdlight emitting element having a third organic compound layer arearranged, and a portion of the first organic compound layer and aportion of the second organic compound layer overlap with each other inthe first light emitting element.

Also, according to a structure 3 of the present invention disclosed inthis specification, there is provided a light emitting device comprisinga plurality of light emitting elements, each having a cathode, anorganic compound layer contacting the cathode, and an anode contactingthe organic compound layer, in which: a first light emitting elementhaving a first light emitting layer, a second light emitting elementhaving a second light emitting layer, and a third light emitting elementhaving a third light emitting layer are arranged; a portion of the firstorganic compound layer and a portion of the second organic compoundlayer overlap with each other in the first light emitting element; and aportion of the second organic compound layer and a portion of the thirdorganic compound layer overlap with each other in the second lightemitting element.

Also, in the above-mentioned structure 2 or 3, the first light emittingelement emits light of one color selected from the group consisting ofred, green, and blue. Also, the first light emitting element, the secondlight emitting element, and the third light emitting element each emitlight having a mutually different color.

Further, it is preferable to tightly seal the entire light emittingelement using a sealing substrate, for example a glass substrate or aplastic substrate, during sealing in the structures 1, 2, and 3.

There is a problem with light emitting devices in that external light(light from outside of the light emitting device) made incident topixels which are not emitting light is reflected by rear surfaces of thecathodes (surfaces contacting the light emitting layer), and the rearsurfaces of the cathodes act as a mirror, reflecting external scenery inobservation surfaces (surfaces toward an observer). Further, althoughcircularly polarizing films are bonded to the observation surfaces ofthe light emitting device in order to avoid this problem, the circularlypolarizing films have an extremely high cost, and this is a problem inthat it invites an increase in manufacturing costs.

An object of the present invention is therefore to prevent turning thelight emitting device into a mirrored surface without using a circularlypolarizing film, and to provide a low cost light emitting device inwhich manufacturing costs for the light emitting device are thus lower.Low cost color filters are used by the present invention as a substitutefor the circularly polarizing films. It is preferable to provide colorfilters in the light emitting device for each of the structures 1, 2,and 3 corresponding to each of the pixels in order to increase colorpurity. Furthermore, black color filter portions (black color organicresins) may also be formed overlapping the portions located between thelight emitting regions. In addition, the black color filter portions mayalso overlap with the portions in which parts of different organiccompound layers overlap with each other.

Note that the color filters are formed in the emission direction of theemitted light, that is between the light emitting elements and theobserver. For example, color filters may be bonded to the sealingsubstrate for cases in which light does not pass through the substrateon which the light emitting elements are formed. Alternatively, colorfilters may be formed on the light emitting element substrate if lightpasses through the light emitting element substrate. Circularlypolarizing films thus become unnecessary.

Further, the biggest problem in putting EL elements to practical use isthat the element lifetime is insufficient. Element degradation alsobecomes a large problem as EL layer degradation occurs with theappearance of dark spots spreading along with long time light emission.

To solve this problem, the present invention employs a structure coveredwith a protective film made from a silicon nitride film or a siliconoxynitride film in which a silicon oxide film or a silicon oxynitridefilm is formed as a buffer layer in order to relieve stress in theprotective film.

According to a structure 4 of the present invention, there is provided alight emitting device comprising a plurality of light emitting elements,each having a cathode, a an organic compound layer contacting thecathode, and an anode contacting the organic compound layer, in which:the anode is made from a transparent conductive film; and the anode iscovered with a laminate of a buffer layer and a protective film.

In the above-mentioned structure 4, the buffer layer may be aninsulating film having as its main constituent silicon oxide or siliconoxynitride formed by sputtering (RF sputtering or DC sputtering) or by aremote plasma method, and the protective film may be an insulating filmhaving silicon nitride or silicon oxynitride as its main constituentformed by sputtering.

In addition, the aforementioned structure 4 is extremely useful forcases in which a transparent conductive film (typically ITO) is used asa cathode or an anode and a protective film is formed thereon. Notethat, although there is a danger that impurities contained in thetransparent conductive film (such as In, Sn, and Zn) will mix into asilicon nitride film contacting the transparent conductive film if thesilicon nitride film is formed by sputtering, the impurities can beprevented from mixing into the silicon nitride film by forming thebuffer layer of the present invention between the two films. The mixingin of impurities (such as In and Sn) form the transparent conductivefilm can be prevented by forming the buffer layer in accordance with thestructure 4, and a superior protective film having no impurities can beformed.

Further, it is preferable to use different chambers for the buffer layerand the protective film in a method of manufacturing for achieving thestructure 4. A structure relating to a method of manufacturing of thepresent invention is a method of manufacturing a light emitting devicehaving a plurality of light emitting elements, each light emittingelement having a cathode, an organic compound layer contacting thecathode, and an anode contacting the organic compound layer. Afterforming the anode from a transparent conductive film and the bufferlayer covering the anode using the same chamber, the protective film isformed on the buffer layer using a different chamber.

Further, structures with two different light emission directions can beconsidered for an active matrix light emitting device. One is astructure in which light emitted from an EL element passes through anopposing substrate and out to enter the eye of an observer. The observercan recognize an image from the opposing substrate side in this case.The other structure is one in which light emitted form an EL elementpasses through an element substrate and out to enter the eye of anobserver. In this case the observer can recognize an image from theelement substrate side.

The present invention provides a manufacturing apparatus capable ofmaking both of these structures.

A structure 5 of the present invention according to the presentinvention relates to a manufacturing apparatus including: a loadingchamber; a first conveyor chamber coupled to the loading chamber; anorganic compound layer film formation chamber coupled to the firstconveyor chamber; a second conveyor chamber coupled to the firstconveyor chamber; a metallic layer film formation chamber coupled to thesecond conveyor chamber; a transparent conductive film formationchamber; a protective film formation chamber; a third conveyor chambercoupled to the second conveyor chamber; a dispenser chamber coupled tothe third conveyor chamber; a sealing substrate loading chamber; and asealing chamber.

In the above-mentioned structure 5, the transparent conductive filmformation chamber is provided with a plurality of targets including atleast a target made from a transparent conductive material and a targetmade from silicon. Also, in the above-mentioned structure 5, thetransparent conductive film formation chamber is provided with anapparatus for forming a film by a remote plasma method.

Further, a substrate on which a drying agent is bonded is placed in thesealing substrate loading chamber in the structure 5. In addition, thereis a vacuum exhaust system in the sealing substrate loading chamber.

Further, there are also vacuum exhaust systems in the first conveyorchamber, the second conveyor chamber, the third conveyor chamber, andthe sealing chamber.

Furthermore, the structure 4, in which the buffer layer and theprotective film are formed, can be manufactured with good throughput byusing the manufacturing apparatus shown in the structure 5.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A to 1C are a top view and cross sectional views, respectively,of pixels (3×3);

FIGS. 2A to 2D are graphs showing the relationship between luminance andvoltage;

FIGS. 3A to 3C are a top view and cross sectional views, respectively,of pixels (3×3);

FIG. 4 is a diagram showing a manufacturing apparatus of the presentinvention (Embodiment Mode 2);

FIGS. 5A and 5B are diagrams showing a laminate structure of the presentinvention (Embodiment Mode 2);

FIG. 6 is a diagram showing the structure of an active matrix EL displaydevice;

FIGS. 7A and 7B are diagrams showing the structure of an active matrixEL display device;

FIG. 8 is a diagram showing the structure of an active matrix EL displaydevice;

FIGS. 9A to 9F are diagrams showing examples of electronic equipment;and

FIGS. 10A to 10C are diagrams showing examples of electronic equipment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT MODES

Embodiment modes of the present invention are explained below.

Embodiment Mode 1

The present invention is explained below by an example of a 3×3 sectionof pixels from among many pixels disposed regularly in a pixel portion.

FIG. 1A is a top view. In FIG. 1A, a light emitting region 10R is a redcolor light emitting region, a light emitting region 10G is a greencolor light emitting region, and a light emitting region 10B is a bluecolor light emitting region. A full color light emitting device isachieved by the light emitting regions of the three colors.

Further, FIG. 1B is a cross sectional view of FIG. 1A sectioned along adashed line segment A-A′. In the present invention, a portion of a redcolor light emitting EL layer 17 (for example, an EL layer in which NileRed, a red color luminescent pigment is added to Alq₃) overlaps with aportion of a green color light emitting element 18 (for example, an ELlayer in which DMQd (dimethyl quinacridone) is added to Alq₃), forming alaminate portion 21, as shown in FIG. 1B. Further, a portion of thegreen color light emitting EL layer 18 overlaps with a portion of a bluecolor light emitting EL 19 (for example, an EL layer in which peryleneis added to BAlq), forming a laminate portion 22. Note that although anexample in which only one side (right side edge portion) of the lightemitting regions is overlapped is shown in FIGS. 1A to 1C, there are nolimitations placed on which portions are to be overlapped, provided thata part of a circumferential portion is overlapped. Both edges, an upperside edge, or a lower side edge may also be overlapped.

A structure in which portions of the EL layers may overlap with eachother is used, and therefore high definition and a high aperture ratiocan be achieved with a full color flat panel display using red, green,and blue color light emission without depending on the method employedin forming the organic compound layers (such as ink jet printing,evaporation, or spin coating), or on the film formation precision.

Further, a TFT 1 in FIG. 1B is an element for controlling the amount ofelectric current flowing in the red color light emitting EL layer 17(p-channel TFT or n-channel TFT), and reference numeral 4 denotes one ofa source electrode and a drain electrode, and reference numeral 7denotes the other of them. Further, a TFT 12 is an element forcontrolling the amount of electric current flowing in the green colorlight emitting EL layer 18, reference numeral 5 denotes one of a sourceelectrode and a drain electrode, and reference numeral 8 denotes theother of them. A TFT 3 is an element for controlling the amount ofelectric current flowing in the blue color light emitting EL layer 19,reference numeral 6 denotes one of a source electrode and a drainelectrode, and reference numeral 9 denotes the other of them. Referencenumerals 15 and 16 denote interlayer insulating films made from anorganic insulating material or an inorganic insulating material.

Further, reference numerals 11 to 13 denote organic light emittingelement cathodes (or anodes), and reference numeral 20 denotes anorganic light emitting element anode (or cathode). It is preferable thatp-channel TFTs be used if the electrodes 11 to 13 are anodes, and it ispreferable that n-channel TFTs be used if the electrodes 11 to 13 arecathodes. A material having a small work function (Al, Ag, Li, Ca, ortheir alloys MgAg, MgIn, AlLi, CaF₂, or CaN) may be used if theelectrodes 11 to 13 are cathodes. Further, a material selected form thegroup consisting of Ti, TiN, TiSi_(x)N_(y), Ni, W, WSi_(x), WN_(x),WSi_(x)N_(y)NbN, Mo, Cr, Pt, Zn, Sn, and In, an alloy material havingone of the aforementioned materials as its main constituent, a filmhaving a compound of these materials as its main constituent, or alaminate film of such films may be used if the electrodes 11 to 13 areanodes. Both edge portions of the electrodes 11 to 13 and portionsbetween the edge portions are covered with inorganic insulators 14. Theelectrodes 11 to 13 are formed of Cr as cathodes here. The electrode 20is formed, as an anode, of a transparent conductive film having a highwork function (ITO (indium tin oxide alloy), an alloy of indium oxideand zinc oxide (In₂O₃—ZnO), zinc oxide (ZnO) or the like). Light emittedfrom each light emitting element passes through the anode 20. Further, alaminate film of a metallic thin film through which light passes (suchas MgAg, MgIn, or AlLi) and a transparent conductive film may also beused if the electrodes 11 to 13 are anodes and the electrode 20 is acathode.

A sealing substrate 30 is then bonded by using a sealing material (notshown in the figures) so as to maintain a spacing of approximately 10μm, thus sealing all light emitting elements. In addition, color filtersare formed on the sealing substrate 30, corresponding to each pixel, inorder to increase color purity. A red colorization layer 31 b is formedopposing the red color light emitting region 10R, a green colorizationlayer 31 c is formed opposing the green color light emitting region 10G,and a blue colorization layer 31 d is formed opposing the blue colorlight emitting region 10B. Further, regions outside of the lightemitting regions are shaded by black color portions of the colorfilters, namely shading portions 31 a. Note that the shading portions 31a are structured by a metallic film (chrome or the like) or an organicmaterial film containing a black color pigment.

Circularly polarizing plates are unnecessary in the present inventionbecause the color filters are formed.

FIG. 1C is a cross sectional view for cases in which FIG. 1A is cutalong a dashed line segment B-B′. Edge portions denoted by referencenumerals 11 a to 11 c and portions between the edge portions are alsocovered with the inorganic insulators 14 in FIG. 1C. An example is shownhere in which the red color light emitting EL layer 17 is common, butthe present invention is not limited by this, and the EL layer may alsobe formed for each pixels that emits the same color of light.

An experiment was performed for comparing the relationship between thevoltage applied to the light emitting regions 10R, 10G, and 10B, and theluminance of light emitted by the light emitting regions, and therelationship between the voltage applied to the laminate portions 21 to23 and the luminance of light emitted by these portions. Theexperimental results are shown in FIG. 2D.

The FIG. 2D is a graph showing the relationship between voltage (V) onthe horizontal axis and luminance (cd/m²) on the vertical axis. Datashown by circular marks within FIG. 2D denotes the relationship betweenthe voltage and luminance of light emitting elements structured by threelayers, an anode, an organic light emitting layer, and a cathode.Further, data shown by rectangular marks denotes the relationshipbetween voltage and luminance of light emitting elements structured byfour layers, an anode, a first organic light emitting layer, a secondorganic light emitting layer, and a cathode. The organic light emittinglayers are structured by a laminate of a light emitting layer, a holetransporting layer (HTL) and a hole injecting layer (HIL). In otherwords, the data shown by the rectangular marks in FIG. 2D is a graph ofthe relationship between voltage and luminance of light emittingelements having a laminate structure shown in FIG. 2A. That is, alaminate of an anode, a first organic light emitting layer (a firstlight emitting layer, a first hole transporting layer, and a first holeinjecting layer), a second organic light emitting layer (a second lightemitting layer, a second hole transporting layer, and a second holeinjecting layer), and a cathode.

As shown in FIG. 2D, the luminance of light emitted from the lightemitting elements having the four layer structure of the anode, the twoorganic light emitting layers, and the cathode falls by approximatelyfour orders of magnitude compared to the luminance of light emitted formthe light emitting elements having the three layer structure of theanode, the organic light emitting layer, and the cathode. It can beanticipated that this is due to a reverse direction diode being formedwhen the two organic light emitting layers overlap with each other,wherein it becomes more difficult for electric current to flow. Further,the film thickness becomes thicker, and therefore it can be anticipatedthat the electrical resistance becomes large and it becomes moredifficult for electric current to flow.

Considering how these results correspond to FIGS. 1A to 1C, theluminance of light emitted by the light emitting regions 10R, 10G, and10B can be considered to be the luminance of the laminate structureshown in FIG. 2C, and the luminance of light emitted by the laminateportions 21 to 23 can be considered to be the luminance of the laminatestructure shown in FIG. 2A. The luminance of light emitted by thelaminate portions 21 to 23 therefore is approximately one one-thousandththat of the luminance of light emitted by the light emitting regions10R, 10G, and 10B.

Further, among the organic light emitting layers, at least one layer isused in common, for example the hole injecting layer, and a portion ofthe first organic light emitting layer and a portion of the secondorganic light emitting layer may overlap with each other on the holeinjecting layer. Results similar to those of the laminate structureshown in FIG. 2A are also obtained for the laminate structure shown inFIG. 2B in which the hole injecting layer is common, that is when therelationship between voltage and luminance of light emitting elementshaving a laminate structure of an anode, a first organic light emittinglayer (a first light emitting layer and a first hole transportinglayer), a second organic light emitting layer (a second light emittinglayer, a second hole transporting layer, and the first hole injectinglayer), and a cathode.

Further, an example having a structure that partially differs from thatof FIGS. 1A to 1C is shown in FIGS. 3A to 3C. Note that portions inFIGS. 3A to 3C that are identical to those of FIGS. 1A to 1C useidentical reference numerals for simplicity.

As shown in FIG. 3A, this is an example in which banks 25 made from anorganic resin are formed between the light emitting region 10R and thelight emitting region 10G, and between the light emitting region 10G andthe light emitting region 10B. Although it depends on patterningprecision, it inevitably becomes difficult to make the distance betweenthe light emitting region 10G and the light emitting region 10B narrowerif the banks 25 are formed. In many cases the banks are formed aroundeach of the pixels, but FIGS. 3A to 3C employ a structure in which thebanks are formed for every column of pixels.

Banks are not formed in FIGS. 1A to 1C, and therefore the spacingbetween each of the light emitting regions can be made narrow, and ahigh definition light emitting device can be achieved.

Further, a protective film 33 is formed in order to increase reliabilityin FIGS. 1A to 1C and in FIGS. 3A to 3C. The protective film 33 is aninsulating film having silicon nitride or silicon oxynitride as its mainconstituent. A buffer layer 32 is formed before forming the protectivefilm in order to relieve stresses within the protective film 33. Thebuffer layer 32 may be formed by an insulating film having silicon oxideor silicon oxynitride as its main constituent with use of a DCsputtering apparatus, an RF sputtering apparatus, or an apparatus usinga remote plasma method. Further, emitted light passes through theprotective film in FIGS. 1A to 1C and FIGS. 3A to 3C, and therefore itis preferable that the film thickness of the protective film be as thinas possible.

There is a risk that impurities contained in a transparent conductivefilm (In, Sn, Zn, and the like) will mix into the protective film 33 ifthe transparent conductive film (typically ITO) is used as a cathode oran anode in FIGS. 1A to 1C and FIGS. 3A to 3C, and if the protectivefilm 33 is formed so as to contact the transparent conductive film.Forming the buffer layer 32 between the transparent conductive film andthe protective film can also prevent the mixing of impurities into theprotective film.

Further, although a structure is shown in FIGS. 1A to 1C and 3A to 3C inwhich light is emitted from the EL layers in a direction toward thesealing substrate, passing through the protective film, the presentinvention is of course not limited to this structure. For example, lightmay also be emitted from the EL layers in such a direction as to passthrough the interlayer insulating film. In this case color filters aresuitably formed on the substrate on which the TFTs are formed.

Embodiment Mode 2

A buffer layer and a protective film are explained here using FIGS. 5Aand 5B.

FIG. 5A is a schematic diagram showing an example of a laminatestructure for a case in which light is emitted in the direction of anarrow within the figure. In FIG. 5A, reference numeral 200 denotes acathode (or an anode), reference numeral 201 denotes an EL layer,reference numeral 202 denotes an anode (or a cathode), reference numeral203 denotes a stress relieving layer (buffer layer), and referencenumeral 204 denotes a protective film. A material having lighttransmitting characteristics, an extremely thin metallic film, or alaminate thereof is used as the electrode 202 when light is emitted inthe direction of the arrow in FIG. 5A.

The protective film 204 uses an insulating film obtained by sputteringand having silicon nitride or silicon oxynitride as its mainconstituent. A silicon nitride film can be obtained provided that theprotective film is formed using a silicon target under an atmospherecontaining nitrogen and argon. Further, a silicon nitride target mayalso be used. The buffer layer 203 is formed before forming theprotective film in order to relieve internal film stresses in theprotective film 204. The buffer layer 203 may be formed by an insulatingfilm having silicon oxide or silicon oxynitride as its main constituentand using a DC sputtering apparatus, an RF sputtering apparatus, or anapparatus using a remote plasma method. When using a sputteringapparatus, the buffer layer may be formed using a silicon target underan atmosphere containing oxygen and argon, or under an atmospherecontaining nitrogen, oxygen, and argon. Further, light passes throughthe protective film, and therefore it is preferable that the filmthickness of the protective film be as thin as possible.

Light emitting elements can be protected by using this type ofstructure, and therefore high reliability can be obtained.

FIG. 5B is a schematic diagram showing an example of a laminatestructure for a case in which light is emitted in the direction of anarrow within the figure. In FIG. 4, reference numeral 300 denotes acathode (or an anode), reference numeral 301 denotes an EL layer,reference numeral 302 denotes an anode (or a cathode), reference numeral303 denotes a stress relieving layer (buffer layer), and referencenumeral 304 denotes a protective film.

Light emitting elements can be protected with this structure, similar tothat of FIG. 5A, and therefore high reliability can be obtained.

Further, an example of a manufacturing apparatus (multi-chamber method)capable of separately making the laminate structure of FIG. 5A and thelaminate structure of FIG. 5B is shown in FIG. 4.

In FIG. 4, reference numerals 100 a to 100 k and 100 m to 100 u denotegates, reference numerals 101 and 119 denote delivery chambers,reference numerals 102, 104 a, 107, 108, 111, and 114 denote conveyorchambers, reference numerals 105, 106R, 106B, 106G, 109, 110, 112, and113 denote film formation chambers, reference numeral 103 denotes apreprocessing chamber, reference numerals 117 a and 117 b denote sealingsubstrate loading chambers, reference numeral 115 denotes a dispenserchamber, reference numeral 116 denotes a sealing chamber, and referencenumeral 118 denotes an ultraviolet light irradiation chamber.

Procedures for conveying a substrate on which a TFT and a cathode arealready formed in advance to the manufacturing apparatus and forming thelaminate structure shown in FIG. 5A are shown in FIG. 4.

The substrate on which the TFT and the cathode 200 are formed is firstset into the delivery chamber 101. The substrate is then conveyed to theconveyor chamber 102, which is coupled to the delivery chamber 101. Itis preferable after vacuum evacuation that an inert gas is introducedinto the conveyor chamber to atmospheric pressure so that as littlemoisture and oxygen as possible exist within the conveyor chamber.

Further, a vacuum evacuation processing chamber for pulling a vacuumwithin the conveyor chamber is coupled to the conveyor chamber 102. Amagnetic levitation turbo molecular pump, a cryo-pump, or a dry pump isprovided in the vacuum evacuation processing chamber. It is thuspossible to set vacuum level reached in the conveyor chamber from 10⁻⁵to 10⁻⁶ Pa, and in addition, back diffusion of impurities from the pumpside and the exhaust system can be controlled. An inert gas such asnitrogen gas or a noble basis used as the gas introduced in order toprevent impurities from being introduced inside the apparatus. The gasintroduced within the apparatus is purified to a high level by a gaspurification apparatus before being introduced within the apparatus. Itis therefore necessary to provide a gas purification apparatus wherebygas is introduced into the film formation apparatus after beingpurified. Oxygen, water, and other impurities contained within the gascan thus be removed in advance, and these impurities can consequently beprevented from being introduced inside the apparatus.

Further, it is preferable to perform annealing for degasification inorder to remove moisture and other gasses contained in the substrate.The substrate is conveyed to the preprocessing chamber 103 coupled tothe conveyor chamber 102, and annealing may be performed there. Inaddition, if it is necessary to clean the surface of the cathode, thesubstrate may be conveyed to the preprocessing chamber 103 coupled tothe conveyor chamber 102, and cleaning may be performed there.

A substrate 104 c is next conveyed from the conveyor chamber 102 to theconveyor chamber 104 without being exposed to the atmosphere, and thenconveyed to the film formation chamber 106R by a conveyor mechanism 104b. A red color light emitting EL layer is then suitably formed on thecathode 200. An example in which the red color light emitting EL layeris formed by evaporation is shown here. The surface of the substrate onwhich the film is to be formed is set facing downward in the filmformation chamber 106R. Note that it is preferable that the filmformation chamber be vacuum evacuated before conveying the substratethereto.

For example, evaporation is performed in the film formation chamber 106Rafter vacuum evacuation to a vacuum level equal to or less than 5×10⁻³Torr (0.665 Pa), preferably between 10⁻⁴ and 10⁻⁶ Pa. An organiccompound is gasified in advance by resistance heating duringevaporation, and this scatters toward the substrate during evaporationwhen a shutter (not shown in the figure) is opened. The gasified organiccompound scatters upward, passes through an opening portion (not shownin the figure) formed in a metal mask (not shown in the figure), and isdeposited to the substrate. Note that the temperature (T₁) of thesubstrate is set from 50 to 200° C., preferably between 65 and 150° C.,by a heating means during evaporation.

For cases in which three types of EL layers are formed in order toprovide full color, film formation may sequentially be performed in thefilm formation chambers 106G and 106B in order after film formation inthe film formation chamber 106R is complete.

The substrate is next conveyed from the conveyor chamber 104 to theconveyor chamber 107, without being exposed to the atmosphere, after thepredetermined EL layer 201 is formed on the cathode 200. In addition,the substrate is then conveyed form the conveyor chamber 107 to theconveyor chamber 108 without being exposed to the atmosphere.

The substrate is next conveyed to the film formation chamber 109 by aconveyor mechanism placed within the conveyor chamber 108, and the anode202 made from a transparent conductive film is suitably formed on the ELlayer 201. A plurality of targets are set within the film formationchamber 109 here, and a sputtering apparatus is used having at least atarget made from a transparent conductive material and a target madefrom silicon. The anode 202 and the stress relieving layer 203 cantherefore be formed in the same chamber. Note that a specialized filmformation chamber for forming the stress relieving layer 203 may also beprovided separately. In this case a sputtering apparatus (RF sputteringor DC sputtering) or an apparatus using a remote plasma method may beemployed.

The substrate is next conveyed from the conveyor chamber 108 to the filmformation chamber 113, without being exposed to the atmosphere, and theprotective film 204 is formed on the stress relieving layer 203. Asputtering apparatus prepared with a target made form silicon or atarget made from silicon nitride is provided within the film formationchamber 113 here. A silicon nitride film can be formed by making theatmosphere within the film formation chamber into a nitrogen atmosphere,or an atmosphere containing nitrogen and argon.

The light emitting element covered with the protective film and thestress relieving layer is thus formed on the substrate by the aboveprocesses.

The substrate is next conveyed from the conveyor chamber 108 to theconveyor chamber 111 without being exposed to the atmosphere, and inaddition, is conveyed from the conveyor chamber 111 to the conveyorchamber 114.

The substrate on which the light emitting element is formed is nextconveyed from the conveyor chamber 114 to the sealing chamber 116. Notethat it is preferable to provide a sealing substrate, on which a sealingmaterial is formed, in the sealing chamber 116.

The sealing substrate is set from the outside into the sealing substrateloading chambers 117 a and 117 b. Note that it is preferable to performannealing in advance under a vacuum in order to remove impurities suchas moisture. For example, annealing may be performed within the sealingsubstrate loading chambers 117 a and 117 b. For cases in which a sealingmaterial is formed on the sealing substrate, the sealing substrate isconveyed from the sealing substrate loading chamber to the dispenserchamber 115 after the conveyor chamber 108 is set to atmosphericpressure. A sealing material is then formed for bonding to the substrateon which the light emitting element is formed, and the sealing substratehaving the formed sealing material is conveyed to the sealing chamber116.

The sealing substrate with the formed sealing material and the substrateon which the light emitting element is formed are then bonded to eachother under a vacuum or within an inert gas atmosphere. Note that,although an example in which the sealing material is formed on thesealing substrate is shown here, the present invention is not inparticular limited to this example, and a sealing material may also beformed on the substrate having the formed light emitting element.

The bonded pair of substrates is next conveyed from the conveyor chamber114 to the ultraviolet light irradiation chamber 118. UV light isirradiated in the ultraviolet light irradiation chamber 118, thushardening the sealing material. Note that although an ultravioletsetting resin is used as the sealing material here, there are noparticular limitation placed on the sealing material, provided that itis an adhesive material.

The pair of substrates is then conveyed from the conveyor chamber 114 tothe delivery chamber 119, and taken out.

Processing up through completely sealing the light emitting element intoa hermetic space is thus completed by using the manufacturing apparatusshown in FIG. 4, without being exposed to the atmosphere, and thereforeit becomes possible to manufacture a light emitting device having highreliability.

Note that it is also possible to use an inline film formation apparatus.

Procedures for forming the laminate structure shown in FIG. 5B are shownbelow. A substrate on which a TFT and an anode are formed in advance isconveyed to the manufacturing apparatus shown in FIG. 4.

First, a substrate on which a TFT and the anode 300 are formed is set inthe delivery chamber 101. The substrate is then conveyed to the conveyorchamber 102 coupled to the delivery chamber 101. It is preferable tointroduce an inert gas at atmospheric pressure within the conveyorchamber after performing vacuum evaporation so that as little moistureand oxygen as possible exist within the conveyor chamber. A transparentconductive material is used as a material for forming the anode 300, andan indium tin compound, zinc oxide, and the like can be used. Thesubstrate is next conveyed to the preprocessing chamber 103, which iscoupled to the conveyor chamber 102. Cleaning, oxidation processing,heat treatment processing, and the like may be performed on the surfaceof the anode in the preprocessing chamber. The irradiation ofultraviolet light within a vacuum, or oxygen plasma processing isperformed as a method of cleaning the anode surface. Further, theirradiation of ultraviolet light within an atmosphere containing oxygenmay be performed while heating to a temperature of 100 to 120° C. as anoxidation process, and this is effective for cases in which the anode isan oxide such as ITO. Further, heat treatment may be performed under avacuum at a heat treatment temperature, which the substrate is capableof withstanding, greater than or equal to 50° C., preferably between 65and 150° C., as the heat treatment process. Impurities such as oxygenand moisture adsorbed on the substrate, and impurities such as oxygenand moisture within films formed on the substrate can thus be removed.In particular, EL materials are easily degraded by impurities such asoxygen and water, and therefore it is effective to perform heattreatment within a vacuum before evaporation.

The substrate 104 c is next conveyed from the conveyor chamber 102 tothe conveyor chamber 104 without being exposed to the atmosphere, andthen conveyed to the film formation chamber 105 by the conveyormechanism 104 b. One layer of an EL layer, such as a hole injectinglayer or a hole transporting layer, is then suitably formed on the anode300. An example of forming the EL layer by evaporation is shown here.The surface of the substrate on which the film is to be formed is setfacing downward in the film formation chamber 105. Note that it ispreferable to perform vacuum evacuation within the film formationchamber before conveying the substrate inside.

The substrate is next conveyed to the film formation chamber 106R,without being exposed to the atmosphere, by the conveyor mechanism 104b, and a red color light emitting EL layer is suitably formed on thehole injecting layer or the hole transporting layer.

For cases in which three types of EL layers are formed in order toprovide full color, film formation may be performed in the filmformation chambers 106G and 106B in order after film formation in thefilm formation chamber 106R is complete.

The substrate is next conveyed from the conveyor chamber 104 to theconveyor chamber 107, without being exposed to the atmosphere, after thepredetermined EL layer 301 is formed on the anode 300. In addition, thesubstrate is then conveyed form the conveyor chamber 107 to the conveyorchamber 108 without being exposed to the atmosphere.

The substrate is next conveyed to the film formation chamber 110 or 112by a conveyor mechanism provided within the conveyor chamber 108, andthe cathode 302 made from a metallic material is suitably formed on theEL layer 301. The film formation chamber 111 is an evaporation apparatusor a sputtering apparatus here.

The substrate is next conveyed from the conveyor chamber 108 to the filmformation apparatus 113 without being exposed to the atmosphere, and thestress relieving layer 303 and the protective film 304 are formed. Asputtering apparatus prepared with a target made form silicon, a targetmade from silicon nitride, or a target made form silicon oxide isprovided within the film formation chamber 113 here. A silicon oxidefilm, a silicon oxynitride film, or a silicon nitride film can be formedby making the film formation chamber atmosphere into a nitrogenatmosphere, an atmosphere containing nitrogen and argon, or anatmosphere containing oxygen, nitrogen, and argon.

The light emitting layer covered with the protective film and the stressrelieving layer can thus be formed on the substrate by the aboveprocesses.

Subsequent process steps are identical to the procedures for forming thelaminate structure shown in FIG. 5A, and therefore an explanationthereof is omitted here.

The laminate structure shown in FIG. 5A and the laminate structure shownin FIG. 5B can thus both be formed by using the manufacturing apparatusshown in FIG. 4.

Further, Embodiment Mode 2 can be freely combined with Embodiment Mode1.

The present invention having the above structure is explained in greaterdetail by the embodiments shown below.

Embodiment 1

In this embodiment, an active matrix type light emitting devicemanufactured on an insulating film will be described. FIG. 6 is a crosssectional view of the active matrix type light emitting device. As anactive element, a thin film transistor (hereafter referred to as TFT) isused here, a MOS transistor may also be used.

A top gate TFT (specifically a planar TFT) is shown as an example, abottom gate TFT (typically inversely staggered TFT) may also be used.

In this embodiment, a substrate 800 is used, which is made of bariumborosilicate glass or alumino borosilicate glass, a quartz substrate, asilicon substrate, a metal substrate, or stainless substrate forming aninsulating film on the surface may be used. A plastic substrate havingheat resistance enduring a treatment temperature of this embodiment alsomay be used, and further a flexible substrate may be used.

Next, a silicon oxynitride film is formed as a lower layer 801 of a baseinsulating film on a heat-resistant glass substrate (the substrate 800)with a thickness of 0.7 mm by plasma CVD at a temperature of 400° C.using SiH₄, NH₃, and N₂O as material gas (the composition ratio of thesilicon oxynitride film: Si=32%, O=27%, N=24%, H=17%). The siliconoxynitride film has a thickness of 50 nm (preferably 10 to 200 nm). Thesurface of the film is washed with ozone water and then an oxide film onthe surface is removed by diluted fluoric acid (diluted down to 1/100).Next, a silicon oxynitride film is formed as an upper layer 802 of thebase insulating film by plasma CVD at a temperature of 400° C. usingSiH₄ and N₂O as material gas (the composition ratio of the siliconoxynitride film: Si=32%, O=59%, N=7%, H=2%). The silicon oxynitride filmhas a thickness of 100 nm (preferably 50 to 200 nm) and is laid on thelower layer to form a laminate. Without exposing the laminate to theair, a semiconductor film having an amorphous structure (here, anamorphous silicon film) is formed on the laminate by plasma CVD at atemperature of 300° C. using SiH₄ as material gas. The semiconductorfilm (an amorphous silicon film is used here) is 54 nm (preferably 25 to200 nm) in thickness.

A base insulating film in this embodiment has a two-layer structure.However, the base insulating film may be a single layer or more than twolayers of insulating films mainly containing silicon. The material ofthe semiconductor film is not limited but it is preferable to form thesemiconductor film from silicon or a silicon germanium alloy(Si_(X)Ge_(1-X) (X=0.0001 to 0.02)) by a known method (sputtering,LPCVD, plasma CVD, or the like). Plasma CVD apparatus used may be onethat processes wafer by wafer or one that processes in batch. The baseinsulating film and the semiconductor film may be formed in successionin the same chamber to avoid contact with the air.

The surface of the semiconductor film having an amorphous structure iswashed and then a very thin oxide film, about 2 nm in thickness, isformed on the surface using ozone water. Next, the semiconductor film isdoped with a minute amount of impurity element (boron or phosphorus) inorder to control the threshold of the TFTs. Here, the amorphous siliconfilm is doped with boron by ion doping in which diborane (B₂H₆) isexcited by plasma without mass separation. The doping conditions includesetting the acceleration voltage to 15 kV, the flow rate of gas obtainedby diluting diborane to 1% with hydrogen to 30 sccm, and the dosage to2×10¹² atoms/cm².

Next, a nickel acetate solution containing 10 ppm of nickel by weight isapplied by a spinner. Instead of application, nickel element may besprayed onto the entire surface by sputtering.

The semiconductor film is subjected to heat treatment to crystallize itand obtain a semiconductor film having a crystal structure. The heattreatment is achieved in an electric furnace or by irradiation ofintense light. When heat treatment in an electric furnace is employed,the temperature is set to 500 to 650° C. and the treatment lasts for 4to 24 hours. Here, a silicon film having a crystal structure is obtainedby heat treatment for crystallization (at 550° C. for 4 hours) afterheat treatment for dehydrogenation (at 500° C. for an hour). Althoughthe semiconductor film is crystallized here by heat treatment using anelectric furnace, it may be crystallized by a lamp annealing apparatuscapable of achieving crystallization in a short time.

After an oxide film on the surface of the silicon film having a crystalstructure is removed by diluted fluoric acid or the like, a continuousoscillating solid-state laser and the second to fourth harmonic of thefundamental wave are employed in order to obtain crystals of large grainsize when crystallizing an amorphous semiconductor film. Since the laserlight irradiation is conducted in the air or in an oxygen atmosphere, anoxide film is formed on the surface as a result. Typically, the secondharmonic (532 nm) or third harmonic (355 nm) of a Nd:YVO₄ laser(fundamental wave: 1064 nm) is employed. When using a continuous wavelaser, laser light emitted from a 10 W power continuous wave YVO₄ laseris converted into harmonic by a non-linear optical element.Alternatively, the harmonic is obtained by putting a YVO₄ crystal and anon-linear optical element in a resonator. The harmonic is preferablyshaped into oblong or elliptical laser light on an irradiation surfaceby an optical system and then irradiates an irradiation object. Theenergy density required at this point is about 0.01 to 100 MW/cm²(preferably 0.1 to 10 MW/cm²). During the irradiation, the semiconductorfilm is moved relative to the laser light at a rate of 10 to 2000 cm/s.

Of course, although a TFT can be formed by using the silicon film havinga crystalline structure before the second harmonics of the continuousoscillating YVO₄ laser is irradiated thereon, it is preferable that thesilicon film having a crystalline structure after the laser light isirradiated thereon is used to form the TFT since the silicon filmirradiated the laser light thereon has an improved crystallinity andelectric characteristics of TFT are improved. For instance, although,when TFT is formed by using the silicon film having a crystallinestructure before the laser light is irradiated thereon, a mobility isalmost 300 cm²/Vs, when TFT is formed by using the silicon film having acrystalline structure after the laser light is irradiated thereon, themobility is extremely improved with about 500 to 600 cm/Vs.

After the crystallization is conducted using nickel as a metal elementthat promotes crystallization of silicon, the continuous oscillatingYVO₄ laser is irradiated thereon though, not limited thereof, after thesilicon film is formed having an amorphous structure and the heattreatment is performed for dehydrogenation, and the silicon film havinga crystalline structure may be obtained by the second harmonics of thecontinuous oscillating YVO₄ laser is irradiated.

The pulse oscillation laser may be used for as a substitute for thecontinuous oscillating laser. In the case that the excimer laser of thepulse oscillation is used, it is preferable that the frequency is set to300 Hz, and the laser energy density is set from 100 to 1000 mJ/cm²(typically 200 to 800 mJ/cm²). Here, the laser light may be overlapped50 to 98%.

The oxide film formed by laser light irradiation is removed by dilutedfluoric acid and then the surface is treated with ozone water for 120seconds to form as a barrier layer composed of an oxide film having athickness of 1 to 5 nm in total. The barrier layer here is formed usingozone water but it may be formed by oxidizing the surface of thesemiconductor film having a crystal structure through ultravioletirradiation in an oxygen atmosphere, or formed by oxidizing the surfaceof the semiconductor film having a crystal structure through oxygenplasma treatment, or by using plasma CVD, sputtering or evaporation toform an about 1 to 10 nm thick oxide film. The oxide film formed by thelaser light irradiation may be removed before the barrier layer isformed.

Next, an amorphous silicon film containing argon is formed on thebarrier layer by plasma CVD or sputtering to serve as a gettering site.The thickness of the amorphous silicon film is 50 to 400 nm, here 150nm. The amorphous silicon film is formed in an argon atmosphere with thefilm formation pressure to 0.3 Pa by sputtering using the silicontarget.

Thereafter, heat treatment is conducted in an electric furnace at 650°C. for 3 minutes for gettering to reduce the nickel concentration in thesemiconductor film having a crystal structure. Lamp annealing apparatusmay be used instead of an electric furnace.

Using the barrier layer as an etching stopper, the gettering site,namely, the amorphous silicon film containing argon, is selectivelyremoved. Then, the barrier layer is selectively removed by dilutedfluoric acid. Nickel tends to move toward a region having high oxygenconcentration during gettering, and therefore it is desirable to removethe barrier layer that is an oxide film after gettering.

Next, a thin oxide film is formed on the surface of the obtained siliconfilm containing a crystal structure (also referred to as a polysiliconfilm) using ozone water. A resist mask is then formed and the siliconfilm is etched to form island-like semiconductor layers separated fromone another and having desired shapes. After the semiconductor layersare formed, the resist mask is removed.

The oxide film is removed by an etchant containing fluoric acid, and atthe same time, the surface of the silicon film is washed. Then, aninsulating film mainly containing silicon is formed to serve as a gateinsulating film 803. The gate insulating film here is a siliconoxynitride film (composition ratio: Si=32%, O=59%, N=7%, H=2%) formed byplasma CVD to have a thickness of 115 nm.

Next, a laminate of a first conductive film with a thickness of 20 to100 nm and a second conductive film with a thickness of 100 to 400 nm isformed on the gate insulating film. In this embodiment, a tantalumnitride film with a thickness of 50 nm is formed on the gate insulatingfilm 803 and then a tungsten film with a thickness of 370 nm is laidthereon. The conductive films are patterned by the procedure shown belowto form gate electrodes and wirings.

The conductive materials of the first conductive film and secondconductive film are elements selected from the group consisting of Ta,W, Ti, Mo, Al, and Cu, or alloys or compounds mainly containing theabove elements. The first conductive film and the second conductive filmmay be semiconductor films, typically polycrystalline silicon films,doped with phosphorus or other impurity elements or may be Ag—Pd—Cualloy films. The present invention is not limited to a two-layerstructure conductive film. For example, a three-layer structureconsisting of a 50 nm thick tungsten film, 500 nm thick aluminum-siliconalloy (Al—Si) film, and 30 nm thick titanium nitride film layered inthis order may be employed. When the three-layer structure is employed,tungsten of the first conductive film may be replaced by tungstennitride, the aluminum-silicon alloy (Al—Si) film of the secondconductive film may be replaced by an aluminum-titanium alloy (Al—Ti)film, and the titanium nitride film of the third conductive film may bereplaced by a titanium film. Alternatively, a single-layer conductivefilm may be used.

ICP (inductively coupled plasma) etching is preferred for etching of thefirst conductive film and second conductive film (first etchingtreatment and second etching treatment). By using ICP etching andadjusting etching conditions (the amount of electric power applied to acoiled electrode, the amount of electric power applied to a substrateside electrode, the temperature of the substrate side electrode, and thelike), the films can be etched and tapered as desired. The first etchingtreatment is conducted after a mask made of resist is formed. The firstetching conditions include applying an RF (13.56 MHz) power of 700 W toa coiled electrode at a pressure of 1 Pa, employing CF₄, Cl₂, and O₂ asetching gas, and setting the gas flow rate ratio thereof to 25:25:10(sccm). The substrate side (sample stage) also receives an RF (13.56MHz) power of 150 W to apply a substantially negative self-bias voltage.The area (size) of the substrate side electrode is 12.5 cm×12.5 cm andthe coiled electrode is a disc 25 cm in diameter (here, a quartz disc onwhich the coil is provided). The W film is etched under these firstetching conditions to taper it around the edges. Thereafter, the firstetching conditions are switched to the second etching conditions withoutremoving the mask made of resist. The second etching conditions includeusing CF₄ and Cl₂ as etching gas, setting the gas flow rate ratiothereof to 30:30 (sccm), and giving an RF (13.56 MHz) power of 500 W toa coiled electrode at a pressure of 1 Pa to generate plasma for etchingfor about 30 seconds. The substrate side (sample stage) also receives anRF power of 20 W (13.56 MHz) to apply a substantially negative self-biasvoltage. Under the second etching conditions where a mixture of CF₄ andCl₂ is used, the W film and the TaN film are etched to almost the samedegree. The first etching conditions and the second etching conditionsconstitute the first etching treatment.

Next follows the second etching treatment with the resist mask kept inplace. The third etching conditions include using CF₄ and Cl₂ as etchinggas, setting the gas flow rate ratio thereof to 30:30 (sccm), and givingan RF (13.56 MHz) power of 500 W to a coiled electrode at a pressure of1 Pa to generate plasma for etching for 60 seconds. The substrate side(sample stage) also receives an RF power of 20 W (13.56 MHz) to apply asubstantially negative self-bias voltage. Then, the third etchingconditions are switched to the fourth etching conditions withoutremoving the resist mask. The fourth etching conditions include usingCF₄, Cl₂, and O₂ as etching gas, setting the gas flow rate ratio thereofto 20:20:20 (sccm), and giving an RF (13.56 MHz) power of 500 W to acoiled electrode at a pressure of 1 Pa to generate plasma for etchingfor about 20 seconds. The substrate side (sample stage) also receives anRF power of 20 W (13.56 MHz) to apply a substantially negative self-biasvoltage. The third etching conditions and the fourth etching conditionsconstitute the second etching treatment. At this stage, gate electrode804 and wirings 805 to 807 having the first conductive layer 804 a asthe lower layer and the second conductive layer 804 b as the upper layerare formed.

Next, the mask made of resist is removed for the first doping treatmentto dope with the entire surface using the gate electrodes 804 to 807 asmasks. The first doping treatment employs ion doping or ionimplantation. Here, ion doping conditions are that the dosage is set to1.5×10¹⁴ atoms/cm², and the acceleration voltage is set from 60 to 100keV. As an impurity elements that imparts the n-type conductivity,phosphorus (P) or arsenic (As) is typically used. The first impurityregion (n⁻ region) 822 to 825 are formed in a self-aligning manner.

Masks made of resist are newly formed. At this moment, since the offcurrent value of the switching TFT 903 is lowered, the masks are formedto overlap the channel formation region of a semiconductor layer formingthe switching TFT 903 of the pixel portion 901, and a portion thereof.The masks are formed to protect the channel formation region of thesemiconductor layer forming the p-channel TFT 906 of the driver circuitand the periphery thereof. In addition, the masks are formed to overlapthe channel formation region of the semiconductor layer forming thecurrent control TFT 904 of the pixel portion 901 and the peripherythereof.

An impurity region (n⁻ region) that overlaps with a portion of the gateelectrode is formed by conducting selectively the second dopingtreatment using the masks made of resist. The second doping treatment isemploys ion doping or ion implantation. Here, ion doping is used, theflow rate of gas obtained by diluting phosphine (PH₃) with hydrogen to5% is set to 30 sccm, the dose is set to 1.5×10¹⁴ atoms/cm², and theacceleration voltage is set to 90 keV. In this case the masks made fromresist and the second conductive layer serve as masks against theimpurity element that imparts the n-type conductivity and secondimpurity regions 311 and 312 are formed. The second impurity regions aredoped with the impurity element that imparts the n-type conductivity ina concentration range of 1×10¹⁶ to 1×10¹⁷atoms/cm³. Here, the sameconcentration range as the second impurity region is referred to as a n⁻region.

Third doping treatment is conducted without removing the masks made ofresist. The third doping treatment is employs ion doping or ionimplantation. As impurity elements imparts n-type conductivity,phosphorus (P) or arsenic (As) are used typically. Here, ion doping isused, the flow rate of gas obtained by diluting phosphine (PH₃) withhydrogen to 5% is set to 40 sccm, the dosage is set to 2×10¹⁵ atoms/cm²,and the acceleration voltage is set to 80 keV. In this case the masksmade of resist, the first conductive layer and the second conductivelayer serve as masks against the impurity element that imparts then-type conductivity and third impurity regions 813, 814, 826 to 828 areformed. The third impurity regions are doped with the impurity elementthat imparts the n-type conductivity in a concentration range of 1×10²⁰to 1×10²¹ atoms/cm³. Here, the same concentration range as the thirdimpurity region is referred to as a n⁺ region.

After removing the resist mask and the new resist mask is formed, thefourth doping treatment is conducted. The fourth impurity regions 818,819, 832, 833 and the fifth impurity regions 816, 817, 830, 831 areformed in which impurity elements imparts p-type conductivity are addedto the semiconductor layer forming the p-channel TFT by the fourthdoping treatment.

The concentration of the impurity element that imparts the p-typeconductivity is set from 1×10²⁰ to 1×10²¹ atoms/cm³ to add to the fourthimpurity regions 818, 819, 832, and 833. The fourth impurity regions818, 819, 832, and 833 being region (n⁻ region) are already doped withphosphorus (P) in the previous step but are doped with the impurityelement that imparts the p-type conductivity in a concentration 1.5 to 3times the phosphorus concentration to obtain the p-type conductivity.Here, a region having the same concentration range as the fourthimpurity regions is also called a p⁺ region.

The fifth impurity regions 816, 817, 830, and 831 are formed in theregion overlaps with the taper portion of the second conductive layer.The impurity elements imparts p-type conductivity is added thereto atthe concentration range from 1×10¹⁸ to 1×10²⁰ atoms/cm³. Here, theregion having the same concentration range as the fifth impurity regionsis referred to as p⁻ region.

Through the above steps, an impurity region having the n-type or p-typeconductivity is formed in each semiconductor layer. The conductivelayers 804 to 807 become the gate electrode of TFT.

An insulating is formed to cover almost the entire surface (not shown).In this embodiment, the silicon oxide film having 50 nm in thickness isformed by plasma CVD method. Of course, the insulating film is notlimited to a silicon oxide film and a single layer or laminate of otherinsulating films containing silicon may be used.

The next step is activation treatment of the impurity elements used todope the respective semiconductor layers. The activation step employsrapid thermal annealing (RTA) using a lamp light source, irradiation ofa laser, heat treatment using a furnace, or a combination of thesemethods.

This embodiment shows an example that the insulating film is formedbefore the above-described activation. However, the insulating film maybe formed before the activation.

The first interlayer insulating film 808 made from a silicon nitridefilm is formed. Then, the semiconductor layers are subjected to heattreatment (at 300 to 550° C. for 1 to 12 hours) to hydrogenate thesemiconductor layers. This step is for terminating dangling bonds in thesemiconductor layers using hydrogen contained in the first interlayerinsulating film 808. The semiconductor layers are hydrogenatedirrespective of the presence of the insulating film made from a siliconoxide film. Other hydrogenation methods employable include plasmahydrogenation (using hydrogen excited by plasma).

Next, a second interlayer insulating film 809 a is formed on the firstinterlayer insulating film 808 from an organic insulating material. Inthis embodiment, an acrylic resin film 809 a is formed to have athickness of 1.6 μm.

Formed next are contact holes reaching the conductive layers that serveas the gate electrodes or gate wires and contact holes reaching therespective impurity regions. In this embodiment, etching treatment isconducted several times in succession. Also, in this embodiment, thefirst interlayer insulating film is used as an etching stopper to etchthe second interlayer insulating film, and then the first interlayerinsulating film is etched.

Thereafter, electrodes 835 to 841, specifically, a source wiring, apower supply line, a lead-out electrode, a connection electrode, etc.are formed from Al, Ti, Mo, W, etc. Here, the electrodes and wirings areobtained by patterning a laminate of a Ti film (100 nm in thickness), anAl film containing silicon (350 nm in thickness), and another Ti film(50 nm in thickness). The source electrode, source wiring, connectionelectrode, lead-out electrode, power supply line, and the like are thusformed as needed. A lead-out electrode for the contact with a gatewiring covered with an interlayer insulating film is provided at an endof the gate wiring, and other wirings also have at their endsinput/output terminal portions having a plurality of electrodes forconnecting to external circuits and external power supplies.

A driver circuit 902 having a CMOS circuit in which an n-channel TFT 905and a p-channel TFT 906 are combined complementarily and a pixel portion901 with a plurality of pixels each having an n-channel TFT 903 or ap-channel TFT 904 are formed in the manner described above.

Next, a third interlayer insulating film 809 b made from an inorganicinsulating material is formed on the second interlayer insulating film809 a. The silicon nitride film 809 b with a thickness of 200 nm isformed by sputtering here.

Next, a contact hole is formed so as to reach the connection electrode841 formed in contact with the drain region of the current control TFT904 made from a p-channel TFT. A pixel electrode 834 is formed so as tocontact and overlap with the connection electrode 841. In thisembodiment, the pixel electrode 834 functions as an anode of an organiclight emitting element, and the pixel electrode 834 serves a transparentconductive film in order to transmit the light emission emitted from theorganic light emitting element to the pixel electrode and the substrate.

An inorganic insulator 842 is formed on each end of the pixel electrode834 so as to cover the each end of the pixel electrode 834. It ispreferable that the inorganic insulator 842 is formed from an insulatingfilm containing silicon by sputtering and then patterned. Further, abank formed from an organic insulator may be formed for as a substitutefor the inorganic insulator 842.

Next, an EL layer 843 and the cathode 844 of the organic light emittingelement are formed on the pixel electrode 834 whose ends are covered bythe inorganic insulator 842. In this embodiment, the EL layer 843 may beformed by ink jet method, evaporation, spin coating method and the like.

An EL layer 843 (a layer for light emission and for moving of carriersto cause light emission) may be formed by freely combining a lightemitting layer, an electric charge transporting layer and an electriccharge injection layer. For example, a low molecular weight organic ELmaterial or a high molecular weight organic EL material is used to forman EL layer. An EL layer may be a thin film formed of a light emittingmaterial that emits light by singlet excitation (fluorescence) (asinglet compound) or a thin film formed of a light emitting materialthat emits light by triplet excitation (phosphorescence) (a tripletcompound). Inorganic materials such as silicon carbide may be used forthe electric charge transporting layers and electric charge injectionlayers. Known organic EL materials and inorganic materials can beemployed.

It is said that the preferred material of a cathode 844 is a metalhaving a small work function (typically, a metal element belonging toGroup 1 or 2 in the periodic table) or an alloy of such metal. The lightemission efficiency is improved as the work function becomes smaller.Therefore, an alloy material containing Li (lithium) that is one ofalkali metals is particularly desirable as the cathode material.

Next, a protective film 846 covering the cathode 844 is formed. As theprotective film 846, an insulating film having silicon nitride orsilicon oxynitride as its main constituent may be formed. It ispreferable that a buffer layer 845 is formed in order to relieve a filmpressure of the protective film 846. The protective film 846 preventsthe intrusion of substances such as moisture and oxygen, whichaccelerate deterioration due to oxidization of the EL layer fromoutside. As the buffer layer 845, an insulating film having siliconoxide or silicon oxynitride as its main constituent may be formed. Thebuffer layer 845 can prevent intrusion of impurity elements from thecathode 844 during the film deposition. However, it is not necessary toprovide the protective film or the like in the input/output terminalportions to which an FPC needs to be connected later.

The stage completed so far steps is shown in FIG. 6. Though theswitching TFT 903 and the current supply TFT for an organic lightemitting element (the current control TFT 904) are shown in FIG. 6, itgoes without saying that it is not limited thereof, various circuitsformed from plural TFTs may be provided at the end of the gate electrodeof the TFT.

Next, the organic light emitting element having at least a cathode, anorganic compound layer, and an anode is preferably sealed by a sealingsubstrate or a sealing can to cut the organic light emitting elementcompletely off from the outside and prevent permeation of externalsubstances, such as moisture and oxygen, that accelerate degradation dueto oxidization of the EL layer.

The FPC (flexible printed circuit) is attached to the electrodes of theinput/output terminal portions using an anisotropic conductive material.The anisotropic conductive material is composed of a resin andconductive particles several tens to several hundreds μm in diameterwhose surfaces are plated by Au or the like. The conductive particleselectrically connect the respective electrodes of the input/outputterminal portions with wirings formed in the FPC.

Further, color filters corresponding to the respective pixels are formedon the substrate. By forming the color filters, it is not necessary toform a circular polarizing plate. If necessary, other optical film maybe provided and an IC chip etc. may be mounted.

Through the above steps, a module type light emitting device to which anFPC is connected is completed.

This embodiment may be freely combined with Embodiment Modes 1 or 2.

Embodiment 2

The top surface view and the cross-sectional view of the module typelight emitting device (also referred to as EL module) obtained byEmbodiment 1 are shown.

FIG. 7A is a view of a top surface view of EL module and FIG. 7B is across-sectional view taken along the line of A-A′ of FIG. 7A. FIG. 7Ashows that the base insulating film 401 is formed on the substrate 400(such as a heat resistant glass, for example), and the pixel portion402, the source side driver circuit 404, and the gate side drivercircuit 403 are formed thereon. These pixel portion and driver circuitmay be obtained according to above-mentioned Embodiment 1.

The reference numeral 419 is a protective film. The pixel portion andthe driver circuit portion are covered by the protective film 419. Inaddition, the protective film may be sealed by the cover material 420using the bonding member. A sealing substrate (such as a glass substrateand a plastic substrate) may be used as the cover material 420, and aspace between the EL layer and the cover material 420 may be filled withinert gas. Furthermore, a desiccant agent may be provided in the covermaterial 420 by a double-stick tape.

In addition, reference numeral 408 represents a wiring for transmittingsignals to be inputted into the source side driver circuit 404 and thegate side driver circuit 403, and it receives a video signal and a clocksignal from the FPC (flexible printed circuit) 409 which becomes anexternal input terminal. In addition, here, only FPC is shown in thefigure, but a printed wiring board (PWB) may be attached to this FPC. Alight emitting device in the present specification is assumed to containnot only a light emitting device itself but also a state in which FPC orPWB is attached thereto.

The cross-sectional structure shown in FIG. 7B is described. A baseinsulating film 401 is formed on the substrate 400. The pixel portion402 and the gate side driver circuit 403 are formed over the insulatingfilm 401. The pixel portion 402 is composed of the current control TFT411 and plural pixels including the pixel electrode 412 that isconnected electrically to the drain of the current control TFT 411. Inaddition, the gate side driver circuit 403 is formed by using a CMOScircuit that is combined with the n-channel TFT 413 and the p-channelTFT 414.

The TFTs (including 411, 413, and 414) may be manufactured according ton-channel TFT of Embodiment 1 and p-channel TFT of Embodiment 1. Thoughonly the current supply TFT for the organic light emitting element (thecurrent control TFT 411) is shown in FIG. 7, it goes without saying thatit is not limited thereof, various circuits formed from plural TFTs maybe provided at the end of the gate electrode of TFT.

The pixel portion 402, the source side driver circuit 404, and the gateside driver circuit 403 are formed on the same substrate according toEmbodiment 1.

The pixel electrode 412 functions as a cathode of the light emittingelement (OLED). The inorganic insulator 415 is formed at the both endsportion of the pixel electrode 412. The organic compound layer 416 andthe anode 417 of the light emitting element are formed on the pixelelectrode 412.

As the organic compound layer 416, it should be appreciated that theorganic compound layer (a layer for carrying out light emission andmovement of carriers therefore) may be formed by freely combining alight emitting layer, an electric charge transport layer or an electriccharge injection layer.

The anode 417 functions as a common wiring to all pixels, and iselectrically connected to an FPC 409 through a connection wiring 408.Further, elements which are contained in the pixel portion 402 and thegate side driver circuit 403 are all covered by a protective film 419.

The protective film may be formed on the entire surface including theback surface of the substrate 400. In such a case, it is necessary tocarefully form the protective film so that no protective film is formedat a portion where the external input terminal (FPC) is provided. A maskmay be used to prevent film forming of the protective film at thisposition. The external input terminal portion may be covered with a tapesuch as a tape made of Teflon (registered trademark) used as a maskingtape in a CVD apparatus to prevent film forming of the protective film.The silicon nitride film, the DLC film, or AlNxOy film may be used asthe protective film 419.

The light emitting element constructed as described above is enclosedwith the protective film 419 to completely isolate the light emittingelement from the outside, thus preventing materials such as moisture andoxygen which accelerate degradation of the organic compound layer byoxidation from entering from the outside. Thus, the light emittingdevice having improved reliability is obtained. The steps from thedeposition to the sealing of EL layer may be conducted by using theapparatus shown in FIG. 4.

Another arrangement is conceivable in which a pixel electrode is used asan anode and an organic compound layer and a cathode are made inlamination to emit light in a direction opposite to the directionindicated in FIG. 7. FIG. 8 shows an example of such an arrangement. Thetop view thereof is the same as the top view shown in FIG. 7 and willtherefore be omitted.

The structure shown in the cross-sectional view of FIG. 8 will bedescribed. An insulating film 610 is formed on a substrate 600, and apixel portion 602 and a gate-side drive circuit 603 are formed above theinsulating film 610. The pixel portion 602 is formed by a plurality ofpixels including a current control TFT 611 and a pixel electrode 612electrically connected to the drain of the current control TFT 611. Agate side driver circuit 603 is formed by using a CMOS circuit having acombination of an n-channel TFT 613 and a p-channel TFT 614.

These TFTs (including 611, 613 and 614) may be fabricated in the samemanner as the n-channel TFT of Embodiment 1 and the p-channel TFT ofEmbodiment 1. Though only the current supply TFT for an organic lightemitting element (the current control TFT 611) is shown in FIG. 8, itgoes without saying that it is not limited thereof, various circuitsformed from plural TFTs may be provided at the end of the gate electrodeof TFT.

The pixel electrode 612 functions as an anode of the organic lightemitting element (OLED). Inorganic insulators 615 are formed at oppositeends of the pixel electrode 612, and an organic compound layer 616 and acathode 617 of the light emitting element are formed over the pixelelectrode 612.

The cathode 617 also functions as a common wiring element connected toall the pixels and is electrically connected to a FPC 609 via connectionwiring 608. All the elements included in the pixel portion 602 and thegate-side drive circuit 603 are covered with a protective film 619.Although it is not shown in figure here, it is preferable that a bufferlayer is provided before the formation of the protective film 619 asdescribed in Embodiment Mode 2. In this embodiment, a silicon oxide filmwhich becomes a buffer layer and a silicon nitride film which becomes aprotective film are sequentially formed by sputtering on the cathode 617made form a transparent conductive film.

A cover member 620 is bonded to the element layer by an adhesive.Further, color filters 621 corresponding to the respective pixels areprovided in the cover member 620 in order to increase color purity. Byproviding the color filters 621, it is not necessary to provide acircular polarizing plate. Further, a desiccant may be set in the covermember 620.

In FIG. 8, the pixel electrode used as the anode while the organiccompound layer and the cathode are formed in lamination, so that thelight is emitted in the direction shown by the arrow in FIG. 8.

While the top gate TFTs have been described by way of example, thepresent invention can be applied irrespective of the TFT structure. Forexample, the present invention can be applied to bottom gate (inverselystaggered structure) TFTs and staggered structure TFTs.

This embodiment may be freely combined with any one of Embodiment Modes1 to 2, and Embodiment 1.

Embodiment 3

By implementing the present invention, EL modules (active matrix ELmodule and passive EC module) can be completed. Namely, by implementingthe present invention, all of the electronic equipments into which thevarious modules are built are completed.

Following can be given as such electronic equipments: video cameras;digital cameras; head mounted displays (goggle type displays); carnavigation systems; car stereos; personal computers; portableinformation terminals (mobile computers, mobile phones, electronic booksetc.) etc. Examples of these are shown in FIGS. 9A to 9F and 10A to 10C.

FIG. 9A is a personal computer which comprises: a main body 2001; animage input section 2002; a display section 2003; and a keyboard 2004etc.

FIG. 9B is a video camera which comprises: a main body 2101; a displaysection 2102; a voice input section 2103; operation switches 2104; abattery 2105 and an image receiving section 2106 etc.

FIG. 9C is a mobile computer which comprises: a main body 2201; a camerasection 2202; an image receiving section 2203; operation switches 2204and a display section 2205 etc.

FIG. 9D is a goggle type display which comprises: a main body 2301; adisplay section 2302; and an arm section 2303 etc.

FIG. 9E is a player using a recording medium in which a program isrecorded (hereinafter referred to as a recording medium) whichcomprises: a main body 2401; a display section 2402; a speaker section2403; a recording medium 2404; and operation switches 2405 etc. Thisapparatus uses DVD (digital versatile disc), CD, etc. for the recordingmedium, and can perform music appreciation, film appreciation, games anduse for Internet.

FIG. 9F is a digital camera which comprises: a main body 2501; a displaysection 2502; a view finder 2503; operation switches 2504; and an imagereceiving section (not shown in the figure) etc.

FIG. 10A is a mobile phone which comprises: a main body 2901; a voiceoutput section 2902; a voice input section 2903; a display portion 2904;operation switches 2905; an antenna 2906; and an image input section(CCD, image sensor, etc.) 2907 etc.

FIG. 10B is a portable book (electronic book) which comprises: a mainbody 3001; display portions 3002 and 3003; a recording medium 3004;operation switches 3005 and an antenna 3006 etc.

FIG. 10C is a display which comprises: a main body 3101; a supportingsection 3102; and a display portion 3103 etc.

In addition, the display shown in FIG. 10C has small and medium-sized orlarge-sized screen, for example a size of 5 to 20 inches. Further, tomanufacture the display part with such sizes, it is preferable tomass-produce by executing a multiple pattern using a substrate sized 1×1m.

As described above, the applicable range of the present invention isextremely large, and the invention can be applied to electronicequipments of various areas. Note that the electronic devices of thisembodiment can be achieved by utilizing any combination of constitutionsin Embodiment Modes 1 to 2, and Embodiments 1 to 2.

Extremely high cost circularly polarizing plates become unnecessary inaccordance with the present invention, and therefore manufacturing costscan be reduced.

Further, high definition, a high aperture ratio, and high reliabilitycan be achieved for a full color flat panel display using red, green,and blue color emission light.

1-25. (Canceled).
 26. A portable information terminal comprising: atleast one light emitting element comprising: a first light emittingregion, the first light emitting region comprising a first organiccompound layer between a cathode and an anode; a second light emittingregion adjacent to the first light emitting region, the second lightemitting region comprising the first organic compound layer and a secondorganic compound layer overlapped with the first organic compound layerbetween the cathode and the anode.
 27. A portable information terminalaccording to claim 26, wherein a light emitting element adjacent to theat least one light emitting element has the second light emitting layer,and wherein color of the light emission of the second light emittinglayer is different from that of the first light emitting layer.
 28. Aportable information terminal comprising: at least one first lightemitting element, the at least one first light emitting elementcomprising a first organic compound layer between a first electrode anda second electrode; at least one second light emitting element, the atleast one second light emitting element comprising a second organiccompound layer between the first electrode and the second electrode; andat least one third light emitting element, the at least one third lightemitting element comprising a third organic compound layer between thefirst electrode and the second electrode, wherein the first organiccompound layer overlaps a part of the second organic compound layer inthe first light emitting element.
 29. A portable information terminalcomprising: at least one first light emitting element, the at least onefirst light emitting element comprising a first organic compound layerbetween a first electrode and a second electrode; at least one secondlight emitting element, the at least one second light emitting elementcomprising a second organic compound layer between the first electrodeand the second electrode; and at least one third light emitting element,the at least one third light emitting element comprising a third organiccompound layer between the first electrode and the second electrode,wherein the first organic compound layer overlaps a part of the secondorganic compound layer in the first light emitting element, and whereinthe second organic compound layer overlaps a part of the third organiccompound layer in the second light emitting element.
 30. A portableinformation terminal according to claim 28, wherein: the first lightemitting element emits light of one color selected from the groupconsisting of red, green, and blue.
 31. A portable information terminalaccording to claim 29, wherein: the first light emitting element emitslight of one color selected from the group consisting of red, green, andblue.
 32. A portable information terminal according to claim 28,wherein: the first light emitting element, the second light emittingelement, and the third light emitting element each emit light having amutually different color.
 33. A portable information terminal accordingto claim 29, wherein: the first light emitting element, the second lightemitting element, and the third light emitting element each emit lighthaving a mutually different color.
 34. A portable information terminalaccording to claim 26, further comprising color filters corresponding toeach pixel.
 35. A portable information terminal according to claim 28,further comprising color filters corresponding to each pixel.
 36. Aportable information terminal according to claim 29, further comprisingcolor filters corresponding to each pixel.
 37. A portable informationterminal according to claim 26, wherein the portable informationterminal is selected from the group consisting of a mobile computer, amobile phone and an electronic book.
 38. A portable information terminalaccording to claim 28, wherein the portable information terminal isselected from the group consisting of a mobile computer, a mobile phoneand an electronic book.
 39. A portable information terminal according toclaim 29, wherein the portable information terminal is selected from thegroup consisting of a mobile computer, a mobile phone and an electronicbook.